Donald Trump Jr. called a tweet by his father about Democratic Sen. Elizabeth Warren's Native American heritage "savage" in a social media post Saturday.

Warren officially announced her run for president on Saturday, which drew a tweet from President Trump that referred to the Massachusetts senator as "Pocahontas."

He also added, "See you on the campaign TRAIL, Liz."

It's unclear why he capitalized "trail," though some speculated online afterward that it could have referred to the "Trail of Tears."

The "Trail of Tears" was a forced relocation of the Cherokee, Chickasaw, Choctaw, Muscogee and Seminole tribes in the wake of the Indian Removal Act of 1830. Tens of thousands of Native Americans were removed from their lands and forced to march to Oklahoma, with thousands dying as a result.

ABC News reached out for comment from the White House on the apparent reference, but did not receive a response.

The president's taunts of Warren's ethnicity center around her claims of holding Native American ancestry. The senator took a DNA test last year that showed she was overwhelmingly European, but it did support the existence of an unadmixed Native American ancestor in her pedigree six to 10 generations ago.